[solved] QtSerialPort - Problem with waitForReadyRead() and bytesAvailable()

jlind74

Hello

I can't get the functions waitForReadyRead() and bytesAvailable() to work as I expect them to.

I'm using Qt 4.7.4, Win 7, MinGW compiler.
QtSerialPort downloaded 11 Feb 2013.

The code in short is:
@
openSerialPort();
if(serial->isOpen())
{
serial->flush();

    RS232Cmd[0] = 0x1B; // 2 bytes, Esc A
    RS232Cmd[1] = 'A';

    serial->write(RS232Cmd,2);
    serial->waitForBytesWritten(100);

    bTest = serial->waitForReadyRead(5000);
    qDebug("w %d", bTest);

    temp_value  = serial->bytesAvailable();
    temp_value2 = serial->read(RS232Buffer, 8);
    qDebug("a %d", temp_value);
    qDebug("r %d", temp_value2);

    closeSerialPort();
}

@

The output I get is this:
@
w 0
a 0
r 0
@

First of all, with the 5000 parameter to waitForReadyRead(); I expect the program to wait 5 seconds before displaying the debug output if no data comes in, but there is no wait time that I can notice.

Second, I can see on the oscilloscope that the two bytes ('Esc' + 'A') are sent and that a 8 byte reply is received within 2ms.

Third, with a terminal program I can verify that the 8 byte reply is correctly received on the PC.

Any ideas on what's going wrong?
Or have I misunderstood the functionality of these functions?

kuzulis

Yes, it is a bug. Thx for posting.

Patch to fix it here: https://codereview.qt-project.org/#change,47729

You can wait and update repo after applied this patch,
or make changes yourself.

jlind74

Thanks kuzulis,

I changed line 161 in qserialport_win.cpp from:
@
return error;
@
to
@
return !error;
@

and now my simplified example works.

Now, I can start working on the more complex software.

kuzulis

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